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Tech Bulletin #5, abridged
Replacing Turbochargers and Exhaust Manifolds

Modifications to turbocharger on production cars were introduced in stages:

Version I = exhaust in and out connections without recess, with gaskets
Version II = exhaust in with recess and fill-in gasket seal, exhaust out without recess, with gasket
Version III = exhaust in and out connections with recess and fill-in gasket seals
Note
Flanges from exhaust manifold and tailpipe to turbocharger have not been modified

 

Turbocharger Comparison Table

Engine Type Model Year Turbocharger Part No. Version Nameplate No.
M 31.02 1980 931 123 004 04
931 123 004 05
931 123 004 06
I
II
III
5326 970 6401
5326 970 6404
5326 970 6406
M 31.04 1981 931 123 004 07 III 5326 970 6020

 

Note
Turbochargers on 1980 models are not interchangeable with those on 1981 models.

 

Exhaust manifold changes

Exhaust Manifold, Part No. 931 111 093.02, for 1980 cars, has been replaced by reinforced manifold, Part No. 931 111 096 00.

This new-type manifold has recess for fill-in gasket seal in flange to by-pass pipe.

When installing new-type exhaust manifold for the first time, use by-pass pipe, Part No. 931 123 033 04, and fill-in gasket seal, Part No. 931 123 195 00. The new by-pass pipe can be connected to the old manifold without recess.

CAUTION
The fill-in gasket seal and never the old-type gasket must be used on recessed flange connections.

Exhaust manifold studs

If turbo exhaust-manifold studs loosen or break,

install new studs of different material, Part No., 900 081 053 00
also always install new self-locking nuts, Part No., N900 730 01